Hi Dappy,
Dappy wrote:Is this some kind of code violation?
Yes, absolutely.
The shingles are required to be installed in accordance with the manufacturer's installation instructions and the code, and what the code does not address (some codes are not as specific as other codes and I don't know where you are or what codes are in effect there) the manufacturer's installation instructions will address.
Most manufacturer's installation instructions will specify a certain method of installation, which includes placement and location of all fasteners and the method of fastener installation (i.e., driven in straight, not over-driven, not under-driven, not driven at an angle, etc.), with placement and location meaning placement in the shingles below the sealant line, not above the sealant line, not in the sealant line. but not low enough so as the fasteners are exposed and not covered by the next shingle laid above. All spelled out in the installation instructions.
The manufacturer's installation instructions also specify the placement of the shingle above the shingle below and the exposure of the shingle below (exposure is the amount of shingle not covered by the shingle above, for example, if a standard three-tab shingle is 12 inches high by 36 inches wide and the shingle above is placed over the first shingle covering 7 inches of the first shingle, the lower shingle as 5 inches "exposed", that is the "exposure" of the shingle and the exposure is also specified in the installation instructions).
What does it do to the warranty?
Those exposed nails, and excessive exposure of the shingles, along with other things the roofer did incorrectly, may well negate the warranty as many, if not most, manufacturers look for installation and other problems to use to void the warranty. Those exposed nails in that many shingles would serve their purpose to back away from the warranty.
I always tell people that if the roofer did not pay attention to the things which shown when the job is completed, just think what they may have not done (or done) for the things which will never be seen again?
Why would we expect a roofer to pay more attention to something no one will see than they do to something everyone will see? We cannot expect that, we can only expect the opposite, and let the roofer prove otherwise if they can.
Yes, those shingles need to be replaced, however, from your description, replacing them and installing the shingles in the roof above may require the removal of all shingles installed above the problem area with all required and necessary work (which may mean a new layer of underlayment be installed from the repair up) to make the installation proper and as new.
Do you have a photo showing the area and the overall roof in that area?